Peristaltic pumping mechanism with geared occlusion rollers

ABSTRACT

A peristaltic pumping mechanism includes a spacer plate having a plurality of axle shafts for rotatably engaging a plurality of geared occlusion rollers. A rotatable drive gear meshes with the geared occlusion rollers and causes them to rotate. Smooth roller portions of the geared occlusion rollers frictionally engage and compress a flexible tube. Rotation of the geared occlusion rollers in contact with the flexible tube causes the occlusion rollers to migrate along the tube, thereby providing peristaltic pumping.

FIELD OF THE INVENTION

This invention relates generally to peristaltic pumps and, moreparticularly, to a peristaltic pumping mechanism having a compressionmechanism comprised of interchangeable geared occlusion rollers.

BACKGROUND

A typical peristaltic pump includes a compressible tube for carrying afluid. The tube generally has an upstream inlet, a downstream outlet anda curved portion oriented in a horseshoe-like or circular path. Thecurved portion is typically supported on its outermost surface against acurved stationary surface such as the interior wall of an enclosure forthe pump. Near the upstream inlet, a rotor-mounted (or cage-mounted)roller engages and progressively squeezes the tube against the surface.The squeezing force is of sufficient magnitude to at least partiallycompress and generally occlude the internal passage of the tube. Thisocclusion is carried around the curved portion by the roller, forcingfluid ahead of the occlusion toward the downstream outlet portion of thetube. As fluid ahead of the occlusion is discharged through thedownstream outlet, the expansion or restitution of the tube in the wakeof the occlusion creates a suction that draws in more fluid through theupstream inlet, and the cycle repeats.

The unique pumping properties of peristaltic pumps make them ideallysuited for certain applications. For example, peristaltic pumps arewidely used in applications where constant metering of fluids atrelatively low flow rates is desired; applications requiring the fluidsbeing pumped to remain free of contamination; applications requiring thefluid path to remain clean or sterile; and applications where corrosive,caustic or hazardous fluids must be pumped without the fluid directlycontacting any components of the pump mechanism other than the tubing.

Despite these advantages, conventional peristaltic pumps sufferdrawbacks, one being complexity of the pumping mechanisms. Suchmechanisms often include an intricate arrangement of many smallcomponents comprised of various materials, which complicatesmanufacturing and maintenance and results in relatively high costs. Suchcomplexity also creates serious quality control issues, as it providesincreased opportunity for defects and failures.

Another shortcoming is the inability to conveniently alter the rate ofthe pumping mechanism. Thus far, solutions generally entail adjustingthe speed of the motor that drives the pumping mechanism or adjustinggear ratios of a gear train that links the motor to the pumpingmechanism. While motor speed may be adjusted by replacing the motor orusing electrical components to control the speed, each of theseapproaches increases overall cost and complexity. Additionally, as mostdrive train assemblies do not readily accommodate additional orreplacement gears, the entire gear train would have to be replaced atconsiderable effort and cost.

Yet another shortcoming is that conventional pumping mechanisms do notdrive (i.e., provide rotational power to) the occlusion rollers. Insteada cage drags the rollers over the tube. This conventional approach isbelieved to be inefficient, requiring a more powerful motor andconsuming more electrical power than would otherwise be required if therollers were each rotationally driven allowing them to ride over thetubes. Additionally, this conventional approach is conducive topremature wear and tear on the tube, especially if a roller fails tofreely rotate.

Thus, a peristaltic pumping mechanism is needed that simplifiesmanufacturing and maintenance, reduces cost, facilitates mechanicallyaltering the pumping rate, and/or avoids premature abrasive wear of thetube.

SUMMARY

The invention solves the problems and/or overcomes the drawbacks anddisadvantages of the prior art by providing a pumping mechanism thatincludes a first rotatable geared occlusion roller having a first rollerportion and a first geared portion. The first roller portion of thefirst geared occlusion roller is configured to compress the flexibletube of a peristaltic pump upon contact therewith. The pumping mechanismalso includes a rotatable drive gear having a geared portion configuredto operably engage the first geared portion of the first rotatablegeared occlusion roller. The rotatable drive gear is configured torotate and cause the first rotatable geared occlusion roller to rotate.

In another aspect of the present invention, the peristaltic pumpingmechanism includes a plurality of rotatable geared occlusion rollers,each having a first roller portion and a first geared portion. The firstroller portions are configured to compress the flexible tube of aperistaltic pump upon contract therewith. The mechanism also includes arotatable drive gear having a first driving geared portion configured tooperably engage the first geared portion of each rotatable gearedocclusion roller. Rotation of the drive gear causes each rotatablegeared occlusion roller to rotate. A spacer plate having an axle shaftfor rotatably engaging each rotatable geared occlusion roller is alsoprovided. The spacer plate has a drive shaft opening for receiving arotatable drive shaft to engage and rotate the drive gear.

In yet another aspect of the present invention, a peristaltic pump isprovided that incorporates a pumping mechanism according to theprinciples of the invention. The pump includes a housing and a flexiblecurved tube within the housing. The flexible curved tube has an inletend and an outlet end. The housing also has an inlet and an outlet, towhich the tube inlet and outlet are fluidly connected. A rotatable driveshaft is provided for engaging a drive gear of the pumping mechanism.

The pumping mechanism includes a plurality of rotatable geared occlusionrollers, each having a first roller portion and a first geared portion.The first roller portions are configured to compress the flexible tubeupon contract therewith. The mechanism also includes a drive gear havinga first driving geared portion configured to operably engage the firstgeared portion of each rotatable geared occlusion roller.

A spacer plate having an axle shaft for rotatably engaging eachrotatable geared occlusion roller is also provided. The spacer plate hasa drive shaft opening for receiving a rotatable drive shaft to engageand rotate the drive gear.

An end of the drive shaft passes through an opening in the spacer plate.The drive gear engages the end. Rotation of the drive gear causes eachrotatable geared occlusion roller to rotate.

At least one of the rotatable geared occlusion rollers frictionallyengages and compresses the flexible tube at all times during operation.As a geared occlusion roller in contact with the flexible hose rotates,it rides or migrates along the length of the flexible tube, causing thespacer plate to rotate.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the presentinvention will become better understood with reference to the followingdescription, appended claims, and accompanying drawings, where:

FIG. 1 conceptually depicts an exemplary pumping mechanism in aperistaltic pump housing in accordance with a preferred implementationof the present invention;

FIG. 2 conceptually depicts a front perspective of a pumping mechanismin accordance with a preferred implementation of the present invention;

FIGS. 3A and 3B show front and side views of a spacer plate inaccordance with a preferred implementation of the present invention;

FIG. 4 shows a perspective view of a geared occlusion roller inaccordance with a preferred implementation of the present invention; and

FIG. 5 shows front, side and back views of a geared occlusion roller inaccordance with an implementation of the present invention.

DETAILED DESCRIPTION

Referring now to FIG. 1, a peristaltic pumping mechanism in accordancewith an exemplary embodiment of the present invention includes a housing100, a flexible tube 105, a drive gear 150, a spacer plate 160 (notshown), and a plurality of geared occlusion rollers 135-145. A rotatabledrive shaft 155 engages the drive gear 150. The drive gear 150 isfixedly mounted at its center on the drive shaft 155. The drive shaft155 may be operably coupled to a motor and/or drive train (not shown) toprovide rotational motion. Each geared occlusion roller 135-145 mesheswith the drive gear 150. Rotation of the drive shaft 155 causes thedrive gear 150 to rotate, which causes the geared occlusion rollers135-145 to rotate in an opposite direction about their central axes. Theexemplary pumping mechanism also includes an inlet 110 and outlet 115fluidly coupled to the flexible tube 105 for fluid flow. A plurality ofthreaded mounting holes 120-130 for receiving screws are also providedto attach a cover (not shown) to the housing 100.

Referring now to FIG. 2, an exemplary spacer plate 160, with a drivegear 150 and geared occlusion rollers 135-145 is shown. The spacer plate160 defines the position of the drive gear 150 and the position of eachocclusion roller 135-145 relative to the drive gear. While a circularplate is depicted, the plate may have other shapes and accommodate moreor fewer occlusion rollers without departing from the scope of thepresent invention.

Referring now to FIGS. 3A and 3B, front and side views of an exemplaryspacer plate 160 are provided. Occlusion rollers 135-145 are rotatablymounted to axle shafts 305-315. The axle shafts 305-315 may benon-rotatable shafts on which the occlusion rollers rotate, or rotatableshafts which rotate with the occlusion rollers. Furthermore, the axleshafts 305-315 may be an integral part of the spacer plate 160 orseparate shaft components attached to the spacer plate 160. As the axleshafts accommodate the occlusion rollers, the height and diameter of theshafts should enable the axle shafts 305-315 to operably engageocclusion rollers and allow the occlusion rollers to freely rotate onthe axle shaft, without substantial play.

A drive shaft opening 320 in the spacer plate 160, enables a drive shaftto protrude through the spacer plate. The opening accommodates the driveshaft 155. In a preferred implementation, the spacer plate 160 is freefloating, thereby allowing the drive shaft 155 to rotate at a differentRPM from the spacer plate. Thus, the drive shaft 155 may freely rotatethrough the opening 320. When the drive gear 150 is placed on the driveshaft 155, rotation of the drive shaft 155 will cause the drive gear 150to rotate, which will cause the engaged occlusion rollers 135-145 torotate about their corresponding axle shafts 305-315. The invention thususes a planetary gear approach to drive occlusion rollers 135-145.Frictional engagement of the rotating occlusion rollers 135-145 with thetube 105, will cause the occlusion rollers 135-145 to revolve around thedrive gear, thus causing the spacer plate 160 to rotate.

The spacer plate 160 is preferably comprised of a durable plastic orpolymeric material, such as polyvinyl chloride (PVC), polyethylene,polypropylene, polystyrene, acrylics, cellulosics,acrylonitrile-butadiene-styrene terpolymers, urethanes, thermo-plasticresins, thermo-plastic elastomers (TPE), acetal resins, polyamides,polycarbonates, nylons or polyesters. Many other materials may be usedalone or in combination with the aforementioned materials and/or othermaterials, without departing from the scope of the present invention.Preferably the material is relatively inexpensive, exhibits acceptablephysical properties including durability, and is easy to use inconventional manufacturing operations. The material may further includeformulations and/or additives to provide desired properties such astransparency or desired colors, structural enhancement, and lubricity.

The spacer plate 160 may be produced using any suitable manufacturingtechniques known in the art for the chosen material, such as (forexample) injection or compression molding or casting. Preferably themanufacturing technique is suitable for mass production at a relativelylow cost per unit, and results in an acceptable product with aconsistent quality.

Referring now to FIG. 4, an exemplary geared occlusion roller 400 isshown. The generally cylindrically shaped gear occlusion roller 400includes a roller portion 415 for engaging and occluding the flexibletube 105. Preferably the roller portion 415 is relatively smooth, so asto not abrade or otherwise prematurely damage the tube 105. In apreferred implementation, each geared occlusion roller 400 furtherincludes two sets of gears, each having the same number of gear teethand pitch diameter. One set of gears, i.e., the protruding gears 410,has teeth extending outwardly beyond the roller portion 415 diameter.The other set of gears, i.e., the recessed gears 420, has teeth thatmatch the diameter of the roller portion 415. A bore 510 extends axiallythrough the center of the geared occlusion roller 400. A portion of thebore 505 may be circular and have a diameter suitable for engaging anaxle shaft 305-315. For example, referring to FIG. 5, the bored portionstarting at the end with recessed gears 420 and extending to the centerof the roller portion 415, may be circular 505 in cross section. Theremaining portion 405 of the bore 510 may be keyed, e.g., non-circularin shape, to securely engage the drive shaft 155. For example, the keyedportion 405 of the bore 510 may include a flat surface to engage a driveshaft 155 also having a flat surface. Thus, rotation of the drive shaft155 will compel rotation of the geared occlusion roller 400, withoutslippage.

Advantageously, such a geared occlusion roller may function as either anocclusion roller 135-145 or as a drive gear 150, effectively reducingthe number of different types of parts required. As a drive gear 150, itcould be mounted such that the keyed end 405 engages the keyed driveshaft 155. As an occlusion roller, it could be mounted such that thecircular portion 505 of the bore 510 engages the axle shaft 305. Eachgeared occlusion roller 135-145 is therefore interchangeable with thedrive gear 150, and vice versa.

Illustratively, referring to FIG. 6, a geared occlusion roller assemblywith four geared occlusion rollers is shown. One geared occlusion rollerserves as drive gear 150. The keyed end 405 is adjacent to the spacerplate 160. The remaining geared occlusion rollers serve as occlusionrollers 135-145. Each occlusion roller has a circular end 505 adjacentto the spacer plate to rotatably engage an axle shaft 305-315. Recessedgear portion 420 of the drive gear 150 engages protruding gear portion410 of each occlusion roller 135-145. Protruding gear portion 420 ofeach occlusion roller 135-145 engages recessed gear portion 410 of thedrive gear 150. Thus, the drive gear “oppositely engages” the occlusionrollers, and vice versa.

The distance from the center of the drive gear 150 to the outer smoothroller surface of each geared occlusion roller 135-145 is preferablyapproximately the same as the distance from the center of the housing toan occluded tube 105 within the housing. Thus, the roller portion of thegeared occlusion rollers 135-145 frictionally engage and compress theflexible tube 105 and cause rotation of the spacer plate 160.

In operation, a motor causes the drive gear 150 to rotate, preferably,either directly by causing the shaft 155 to rotate or indirectly via aconventional drive train that may include various gears and/or belts andpulleys arranged to drive the shaft 155. Rotation of the drive gear 150causes the geared occlusion rollers 135-145 to rotate around theircentral axes. In a preferred implementation, at least one gearedocclusion roller will contact the tube 105 at all times. Rotation of ageared occlusion roller in frictional contact with the tube will causethat geared occlusion roller to drive or migrate along the tubing 105.Concomitantly, such driving or migration will cause or assist rotationof the spacer plate 160.

The rotation and revolution speeds of the geared occlusion rollers135-145 (ω_(r)) may generally be determined as a function of therotational speed of the drive gear 150 (ω_(d)) and the pitch diametersof the gears, as is well known in the art.$\omega_{r} = {\omega_{d}\frac{D_{d}}{D_{r}}}$

-   -   where:    -   ω_(r) is the rotational velocity of the geared occlusion        rollers;    -   ω_(d) is the rotational velocity of the drive gear;    -   D_(d) is the pitch diameter of the drive gear; and    -   D_(r) is the pitch diameter of the geared occlusion rollers.

Pumping speed of a peristaltic pump may readily be influenced/controlledby the geometries (e.g., pitch diameters) of the gears.

Those skilled in the art will appreciate that the drive gear 150 andocclusion rollers 135-145 may be different sizes to achieve a differentpumping rate and force transmission. For example, the drive gear mayhave a diameter (i.e., gear pitch diameter) that is approximately halfof the diameter of the occlusion rollers. Such a configuration wouldreduce the pumping rate, as compared to the pumping rate achieved withequally sized gears, by about 50%. Conversely, a drive gear with adiameter twice that of the occlusion rollers will increase the pumpingrate by approximately 100%, in comparison to the rate achieved withequally sized gears. Of course, in either case, the gears of the drivegear and the gears of the occlusion rollers must properly mesh.Additionally, the drive gear and occlusion rollers must be sized to fitthe spacer plate and pump housing and effectuate a desired occlusion inthe tube.

The driving or migration of the geared occlusion rollers 135-145 cause apropagating compression in the flexible tube 105 in contact with theroller surface of the geared occlusion rollers 135-145. Preferably, thecompression is of sufficient magnitude to generally occlude the internalpassage of the tube 105. This occlusion migrates around the curvedportion of the flexible tube 105 as the occlusion rollers 135-145revolve around the drive gear 150, forcing fluid ahead of the occlusiontoward the downstream outlet portion of the tube 105. As fluid ahead ofthe occlusion is discharged through the downstream outlet, the expansionor restitution of the tube 105 in the wake of the occlusion creates asuction that draws in more fluid through the upstream inlet, and thecycle repeats.

In a preferred implementation, the flexible tube 105 includes anupstream inlet 110, a downstream outlet 115 and a curved path betweenthe outlet and inlet. The curved path is preferably circular orsemicircular, but may have other configurations such as a horseshoeshape. A stationary surface, such as a portion of the housing for thepumping mechanism, preferably supports the circular path on itsoutermost side. The diameter of the flexible tube 105 along the circularpath portion is preferably sufficient to accommodate the gearedocclusion rollers 135-145, while being substantially compressed oroccluded at the portion of the tube 105 in contact with the gearedocclusion rollers 135-145.

In a preferred implementation of the present invention, a check valvemeans, such as a one-way valve, may be fluidly connected to the upstreaminlet 110. The valve may allow fluid to enter the upstream inlet 110,but not escape through it.

In a preferred implementation, drive gear 150 and geared occlusionrollers 135-145 are comprised of plastic and are manufactured accordingto industry standards for plastic gears. The resins, additives andmanufacturing process used should preferably produce gears that exhibitacceptable strength, fatigue life, temperature resistance, moistureresistance and dimensional stability. Additives such as glass and/orcarbon may be included to impart desired structural characteristics.Lubricant additives such as polytetrafluoroethylene (PTFE), silicone orgraphite may be compounded into the resin to reduce coefficients offriction. Examples of resins typically used for plastic gears includenylon, acetal copolymer, crystalline resins and linear polyphenylenesulfide.

In an alternative embodiment, a cover for the housing may include aninternal gear track for engaging the protruding gear portions of thegeared occlusion rollers when the cover is placed on the housing. Theinternal gear track may be a circular track. Rotation of the gearedocclusion rollers will thus cause them to travel around the track. Suchtraveling will cause the spacer plate to rotate. This embodiment reducesthe risk of slippage due to low friction between the flexible tube androller portion of the geared occlusion rollers.

An advantage of the present invention is that the pumping mechanism maybe comprised of a relatively small number of parts, as described above.A pumping mechanism in accordance with an exemplary embodiment of thepresent invention includes three key components—a drive gear 105,plurality of geared occlusion rollers 135-145 and a spacer plate 160. Ifthe geared occlusion rollers and the drive gear are the same size, thentwo different types of parts comprise the pumping mechanism. Incomparison, a pumping mechanism of a conventional peristaltic pump mayinclude an intricate arrangement of dozens of components. Having fewercomponents reduces costs, simplifies manufacturing and maintenance andenhances reliability.

Another advantage of the present invention is that the speed of thepumping mechanism can readily be altered by replacing the drive gear 105and geared occlusion rollers 135-145 with those having different pitchdiameters. Of course, the drive gear 105 and geared occlusion rollers135-145 must be of sufficient size to mesh properly and for the rollersurface to occlude the flexible tube of a peristaltic pump. Within thatconstraint, for a given rotation speed of the drive shaft 155, a widerange of revolution speeds of the geared occlusion rollers 135-145, andthus a wide range of rates of progression of an occlusion in theflexible tube 105, may be achieved by altering the ratio of pitchdiameters of the drive gear 105 and geared occlusion rollers 135-145.Furthermore, the process for changing the gears can be sufficientlystraightforward for a mechanically unsophisticated end-user toimplement.

A further advantage of a pumping mechanism in accordance with anexemplary embodiment of the present invention is that it may be utilizedwith commercially available pumping motors and drive trains. Thisreduces engineering and manufacturing costs.

Yet a further advantage of a pumping mechanism in accordance with anexemplary embodiment of the present invention is that the compressionmeans may be changed to alter pump output volumes. The amount ofcompression, which is defined in part by the magnitude of the occlusion,may be altered by substituting geared occlusion rollers having a largeror smaller roller diameter. This allows use of flexible tubes havingvarious diameters in the same pump housing.

Additionally, the pumping mechanism reduces risks of a jammed (i.e.,non-rotating) roller. Motor power is transferred to the occlusionrollers via the engaged drive gear, causing the occlusion rollers torotate. Such rotation reduces abrasive wear on the tube.

Moreover, the pumping mechanism efficiently distributes power. It isbelieved that the use of driven rollers reduces the power required fromthe motor. This may translate into increased motor life, less powerconsumption and reduced size and weight.

While the invention has been described in terms of its preferredembodiments, those skilled in the art will recognize that the inventioncan be practiced with modifications within the spirit and scope of theforegoing detailed description. Such alternative embodiments andimplementations are intended to come within the scope of the presentinvention.

1. A peristaltic pumping mechanism for a peristaltic pump having aflexible tube, said pumping mechanism comprising: a first rotatablegeared occlusion roller having a first roller portion and a first gearedportion, the first roller portion of the first geared occlusion rollerbeing configured to compress the flexible tube upon contact therewith,and a rotatable drive gear having a geared portion configured tooperably engage the first geared portion of the first rotatable gearedocclusion roller, said rotatable drive gear being configured to rotateand cause the first rotatable geared occlusion roller to rotate.
 2. Aperistaltic pumping mechanism as in claim 1, further comprising: aspacer plate, said spacer plate having a first axle shaft for rotatablyengaging the first rotatable geared occlusion roller, and a drive shaftopening for receiving a drive shaft; wherein the rotatable drive gear ispositioned to engage the drive shaft.
 3. A peristaltic pumping mechanismas in claim 2, wherein said spacer plate further includes a second axleshaft, said pumping mechanism further comprising: a second rotatablegeared occlusion roller having a second roller portion and a secondgeared portion, the second roller portion of the second geared occlusionroller being configured to compress the flexible tube upon contacttherewith, and the second geared portion being configured to operablyengage the geared portion of the rotatable drive gear, said secondrotatable geared occlusion roller being rotatably mounted on the secondaxle shaft of the spacer plate.
 4. A peristaltic pumping mechanism for aperistaltic pump having a flexible tube, said pumping mechanismcomprising: a plurality of rotatable geared occlusion rollers, eachhaving a first roller portion and a first geared portion, each firstroller portion being configured to compress the flexible tube uponcontract therewith; and a rotatable drive gear having a first drivinggeared portion configured to operably engage the first geared portion ofeach rotatable geared occlusion roller, said rotatable drive gear beingconfigured to rotate and to thereby cause each rotatable gearedocclusion roller to rotate; and a spacer plate having a plurality ofaxle shafts, one axle shaft for rotatably engaging each rotatable gearedocclusion roller, said spacer plate also having a drive shaft openingfor receiving a rotatable drive shaft to engage and rotate the rotatabledrive gear.
 5. A peristaltic pumping mechanism according to claim 4,configured to cause the spacer plate to rotate upon rotation of therotatable geared occlusion rollers in contact with the flexible tube. 6.A peristaltic pumping mechanism according to claim 5, wherein eachrotatable geared occlusion roller is the same or approximately the samesize.
 7. A peristaltic pumping mechanism according to claim 6, whereinthe drive gear is the same or approximately the same size as eachrotatable geared occlusion roller.
 8. A peristaltic pumping mechanismaccording to claim 7, wherein the drive gear is interchangeable with anyrotatable geared occlusion rollers.
 9. A peristaltic pumping mechanismaccording to claim 6, wherein the drive gear is a different size thaneach rotatable geared occlusion roller.
 10. A peristaltic pumpingmechanism according to claim 6, said mechanism having a pumping rate,the pumping rate being a function of the rotational speed of the drivegear and the ratio of the pitch diameter of the drive gear to the pitchdiameter of the plurality of geared occlusion rollers.
 11. A peristalticpumping mechanism according to claim 6, wherein each rotatable gearedocclusion roller includes a second geared portion, and the rotatabledrive gear includes a second driving geared portion, and the secondgeared portion of each rotatably geared occlusion roller is configuredto engage the second driving geared portion of the drive gear.
 12. Aperistaltic pumping mechanism according to claim 11, wherein the firstgeared portion of each rotatable geared occlusion roller is a protrudinggeared portion and the first driving geared portion of the drive gear isa recessed geared portion.
 13. A peristaltic pumping mechanism accordingto claim 12, wherein the second geared portion of each rotatable gearedocclusion roller is a recessed geared portion and the second drivinggeared portion of the drive gear is a protruding geared portion.
 13. Aperistaltic pumping mechanism according to claim 4 wherein eachrotatable geared occlusion roller is comprised of a plastic or polymericmaterial.
 14. A peristaltic pumping mechanism according to claim 4wherein the drive gear is comprised of a plastic or polymeric material.15. A peristaltic pumping mechanism according to claim 4 wherein thespacer plate is comprised of a plastic or polymeric material.
 16. Aperistaltic pump comprising: a housing, a flexible curved tube withinthe housing, the flexible curved tube having an inlet end and an outletend; the housing having an inlet and an outlet, the inlet end of theflexible curved tube being fluidly connected to the inlet of thehousing, and the outlet end of the flexible curved tube being fluidlyconnected to the outlet of the housing; a rotatable drive shaft; and aperistaltic pumping mechanism according to claim 4, an end of said driveshaft passing through the opening for receiving a drive shaft in thespacer plate, said drive gear fixedly engaging said end of the rotatabledrive shaft, and at least one of said plurality of rotatable gearedocclusion rollers frictionally engaging and compressing the flexibletube.
 17. A peristaltic pump according to claim 16, wherein rotation ofthe drive shaft causes the drive gear to rotate, rotation of the drivegear causes each rotatable geared occlusion roller to rotate, rotationof the at least one of said plurality of rotatable geared occlusionrollers frictionally engaging and compressing the flexible tube causesthe spacer plate to rotate.
 18. A peristaltic pump according to claim17, wherein the drive gear and each rotatable geared occlusion roller iscomprised of a plastic or polymeric material.
 19. A peristaltic pumpaccording to claim 18, wherein the drive gear and each rotatable gearedocclusion roller are the same size.
 20. A peristaltic pump according toclaim 18, wherein the drive gear and each rotatable geared occlusionroller are interchangeable.